Temperament in the clinical differentiation of depressed bipolar and unipolar major depressive patients

OBJECTIVE: To examine differences in temperament profiles between patients with recurrent unipolar and bipolar depression. METHOD: Depressed individuals with recurrent major depressive disorder (MDD) (n = 94) and those with bipolar (n = 59) disorders (about equally divided between types I and II) were recruited by newspaper advertisement, radio and television announcements, flyers and newsletters, and word of mouth. All patients were interviewed using the Structured Clinical Interview for DSM III-R (SCID) and had the severity of their depressive episode assessed by means of the 17-item Hamilton Rating Scale for Depression. All patients filled out the TEMPS-A, a validated instrument. RESULTS: Temperament differences between bipolar and MDD patients were examined using MANCOVA. Overall significant effect of the fixed factor (bipolar vs. unipolar) was noted for the temperament scores [Hotelling's F((5,142)) = 2.47, p < 0.05]. Overall effects were found for age [F((5,142)) = 2.40, p < 0.05], but not for gender and severity of depression [F((5,142)) = 1.65, p = 0.15 and F((5,142)) = 0.66, p = 0.66, respectively]. Dependent variables included the five subscales of the TEMPS-A, but only the cyclothymic temperament scores showed significant between-group differences. LIMITATION: Small bipolar subsample cell sizes did not permit to test the specificity of the findings for bipolar II vs. bipolar I patients. CONCLUSION: The finding that the clyclothymic subscale is significantly elevated in the bipolar vs. the unipolar depressive group supports the theoretical assumptions upon which the scale is based, and suggests that it might become a useful tool for clinical and research purposes.     

Heterogeneity in EEG sleep findings in adolescent depression: unipolar versus bipolar clinical course

Background: EEG sleep measures in child and adolescent subjects with depression have shown considerable variability regarding group differences between depressed and control subjects. This investigation was designed to assess whether some of the observed variability is related to undifferentiated unipolar and bipolar disorders in a sample that was reported previously. Methods: Twenty-eight adolescents who met criteria for unipolar major depression and 35 controls with no lifetime psychiatric disorder participated in a cross-sectional sleep polysomnography study. Approximately 7 years later, follow-up clinical evaluations were conducted in 94% of the original cohort. Clinical course during the interval period was assessed without knowledge of subjects’ initial diagnostic and psychobiological status. Re-analysis of the original sleep data were performed with the added information of longitudinal clinical course. Results: Depressed subjects who had a unipolar course showed reduced REM latency, higher REM density, and more REM sleep (specifically in the early part of the night) compared with depressed adolescents who converted to bipolar disorder and controls who remained free from psychopathology at follow-up. In contrast to the unipolar group, depressed subjects who would later switch to bipolar disorder had demonstrated more stage 1 sleep and diminished stage 4 sleep. Conclusions: These preliminary results indicate that some of the observed variability in EEG sleep measures in adolescent depression appear to be confounded by latent bipolar illness. The findings also suggest that sleep regulatory changes associated with unipolar versus bipolar mood disorders may be different.     

Juvenile and late onset forms of depressive disorder: Genetic and biological characterization of bipolar and unipolar illness — A review

The age of onset of depressive illness may have an association with the genetic character and clinical course of the disorder. There are several genetic models of depressive disorder that are based on differences in age of onset. According to a multifactorial model, for example, a late onset would indicate a smaller genetic and greater environmental component. A correlation has been found between positive family history of affective illness and early age of the first episode. The presence or absence of a family history of affective illness has also been found to be distinguished by pharmacology, physiology, symptomatology, and severity. It is therefore recommended, for purposes of diagnosis and treatment, that a family history be gathered for patients with depressive illness.     

双相障碍抑郁发作与单相抑郁患者个性对比

目的研究双相障碍抑郁发作与单相抑郁患者气质类型和个性因素的差异,为双相障碍抑郁发作和单向抑郁发作的鉴别诊断提供参考。方法根据一定的纳入标准和排除标准对临床上确诊的单相抑郁、双相障碍抑郁发作各60例,应用艾森克人格问卷(EPQ)评定其个性特点,比较两组患者在艾森克人格问卷(EPQ)的个性因素和气质类型上的差异。结果双相障碍抑郁发作患者在气质类型的分布上主要集中在胆汁质,而单相抑郁患者为胆汁质的仅为1/4,两组患者在气质类型(即EPQ的个性象限)的分布上差异有显著性。在EPQ的各个性因素分析上,单相抑郁患者的内外向因素分、情绪稳定性因素分均显著低于双相障碍抑郁发作患者,而掩饰因素分及精神病性因素分的差异无显著意义。结论单相抑郁患者与双相障碍抑郁发作患者在EPQ的个性因素和气质类型上均有显著不同,EPQ测试结果在单相抑郁与双相障碍抑郁发作的鉴别诊断方面有一定的参考价值。     

Trait impulsivity in patients with mood disorders

BACKGROUND: Impulsivity is a key component of the manic behavior of bipolar disorder and is reported to occur in bipolar patients as a stable characteristic, i.e. a trait. Nevertheless, impulsivity has not been widely studied in depressed bipolar patients. We assessed impulsivity in depressed and euthymic bipolar and unipolar patients and healthy controls. We hypothesized that bipolar subjects would have higher levels of trait impulsivity than the comparison groups. METHODS: Twenty-four depressed bipolar, 24 depressed unipolar, 12 euthymic bipolar, and 10 euthymic unipolar patients, as well as 51 healthy subjects were evaluated with the Barratt Impulsiveness Scale (BIS). Analysis of covariance with age and sex as covariates was used to compare mean group differences. RESULTS: Depressed bipolar, euthymic bipolar, and depressed unipolar patients did not differ, and showed greater impulsivity than healthy controls on all of the BIS scales. Euthymic unipolar patients scored higher than healthy controls only on motor impulsivity. LIMITATIONS: Higher number of past substance abusers in the bipolar groups, and no control for anxiety and personality disorders, as well as small sample sizes, limit the reach of this study. CONCLUSIONS: This study replicates prior findings of stable trait impulsivity in bipolar disorder patients, and extends them, confirming that this trait can be demonstrated in depressed patients, as well as manic and euthymic ones. Trait impulsivity may be the result of repeated mood episodes or be present prior to their onset, either way it would influence the clinical presentation of bipolar disorder.     

Differences in functional connectivity in major depression versus bipolar II depression

Background

Objective methods of differentiating unipolar versus bipolar depression would enhance our ability to treat these disorders by providing more accurate diagnoses. One first step towards developing diagnostic methodology is determining whether brain function as assessed by functional MRI (fMRI) and functional connectivity analyses might differentiate the two disorders.

Methods

Fourteen subjects with bipolar II depression and 26 subjects with recurrent unipolar depression were studied using fMRI and functional connectivity analyses.

Results

The first key finding of this study was that functional connectivity of the right posterior cingulate cortex differentiates bipolar II and unipolar depression. Additionally, results suggest that functional connectivity of this region is associated with suicidal ideation and depression severity in unipolar but not bipolar II depression.

Limitations

The primary limitation is the relatively small sample size, particularly for the correlational analyses.

Conclusions

The functional connectivity of right posterior cingulate cortex may differential unipolar from bipolar II depression. Further, connectivity of this region may be associated with depression severity and suicide risk in unipolar but not bipolar depression.     

Association between symptomatic profile and remission following antidepressant treatment in unipolar major depression

Background

To evaluate, in patients affected by an acute major depressive episode, what predictive value certain baseline psychopathological characteristics have with regard to expected therapeutic remission following biological antidepressant treatment (pharmacological/electroconvulsive; non-psychological).

Methods

Six predefined psychopathological characteristics in acute major depressive episode were evaluated using a logistic regression model through a protocolised antidepressant treatment to assess their predictive value with regard to expected remission rate.

Results

The final study sample consisted of 129 subjects affected by an acute major depressive episode. From the baseline evaluation of the anguish/restlessness, reduced emotional reactivity, reduced attention, reduced motor response, feeling of worthlessness, and mood characteristics items, it was possible to correctly classify 88.1% of the sample as remitter/non-remitter with sensitivity of 0.77 and specificity of 0.96. Addition of the 17-item HRSD baseline variable to the regression model increased the capacity for correct classification of the baseline sample by only 0.09%.

Limitations

Protocolised antidepressant treatment was used. The results of this study may not be generalisable to pharmacological treatments not included in this protocol.

Conclusions

The results of this study suggest that certain baseline psychopathological characteristics (and perhaps other clinical variables too) of the acute major depressive episode may be of great use in establishing patient subgroups according to expected clinical remission to the administration of biological antidepressant treatment. This could have considerable consequences for individualised therapeutic decision-making and for future researches (clinical trials included).     

Alcoholism in antisocial and nonantisocial men with unipolar major depression

Men with primary and secondary unipolar major depression were divided into those with and without antisocial personality (ASP). The ASP depressives had a higher rate of alcoholism than the nonASP depressives, and among the nonASP depressives, those with drug abuse had a higher rate of alcoholism than those without drug abuse.The course of depression appeared to be related to the presence of nonaffective psychopathology. Depressed men with additional nonaffective disorders had fewer, but larger episodes than depressed men without, and depressed men with alcoholism had a higher risk of suicide.Our results confirm the close association of alcoholism and ASP and highlight the importance of recognizing nonaffective syndromes in the depressed patient.     

Atypical symptoms in hospitalised patients with major depressive episode: frequency, clinical characteristics, and internal validity

OBJECTIVE: The objective was (1) to assess the frequency of atypical depression (AD) in depressed inpatients; (2) to compare clinical features of patients with atypical and nonatypical depression (Non-AD) (3) to evaluate the meaning of single psychopathological symptoms with special respect to mood reactivity. METHOD: Diagnoses of 1073 inpatients were assessed according to DSM-IV using SCID (Structured Clinical Interview for the DSM-IV) and AMDP (Association for Methodology and Documentation). Diagnosis of atypical depression was defined according to criteria of the DSM-IV specifier for AD. All patients were rated using HAMD-21 (Hamilton Depression Scale). RESULTS: A high percentage of patients met criteria for AD (15.3%, 95% CI 13.0-17.9%). Women were more likely to suffer from AD (OR=1.54, p=0.037). There were no significant differences between AD and Non-AD patients regarding age, HAMD total baseline score, and diagnosis of any bipolar illness. In terms of psychopathology patients with AD were significantly more likely to suffer from somatic anxiety, somatic symptoms, guilt, genital symptoms, depersonalisation and suspiciousness as defined by HAMD-21 items. Interestingly, mood reactivity was not found to be significantly associated with the presence of two or more additional symptoms of AD. LIMITATIONS: Results were assessed by a post-hoc analysis, based on prospectively collected data. Compared to other inpatient samples with MDE, prevalence of bipolar disorder was rather low. CONCLUSION: (1) Frequency of AD may be underestimated, especially in inpatient samples. Further studies of inpatient samples are recommended. (2) Quality of distinct anxiety symptoms may be different in both groups, with AD patients being more likely to suffer from somatic symptoms and somatic anxiety. The presence of suspiciousness and even paranoid phenomena may not exclude a diagnosis of AD, but may be related to rejection sensitivity. (3) The mandatory presence of mood reactivity for the diagnosis of AD needs further consideration, regarding its validity for the concept.     

Psychostimulants for managing unipolar and bipolar treatment-resistant melancholic depression: A medium-term evaluation of cost benefits

Background

We earlier reported an open study of 50 unipolar and bipolar treatment resistant depressed patients indicating that psychostimulants may have differential superiority for the melancholic depressive sub-type. We designed an extension study to examine cost benefits of psychostimulants more closely for those only with melancholic depression.

Method

The sample comprised patients clinically diagnosed with melancholic depression who had failed to respond to and/or experienced significant side-effects with at least two antidepressants. Data were collected for 61 unipolar and 51 bipolar II patients receiving a psyschostimulant for a mean interval of 69 weeks. Benefits and side-effects were assessed.

Results

Effectiveness ratings were similar across unipolar and bipolar sub-sets. Psychostimulants were judged as ‘very’ effective for 20% of patients and ‘somewhat’ effective for 50%. Forty percent judged the psychostimulant as being ‘as effective’ or as ‘superior’ to previously prescribed antidepressants, and worthy of being maintained. Significant side-effects were experienced by 40% of patients, requiring medication to be ceased in 12%. Twenty percent of the bipolar patients experienced a worsening of highs.

Limitations

The study was uncontrolled and retrospective, no formal rater-completed or patient-completed interval measures of severity were completed, while diagnostic judgments about melancholic depression and bipolar disorder were clinically judged.

Conclusions

This open study suggests that psychostimulants may be efficacious antidepressant options for managing unipolar and bipolar melancholia, often seemingly having very rapid onset and generally requiring only low doses, and arguing the need for controlled studies in melancholic patients.     

Sensitivity and specificity of the mood disorder questionnaire and the bipolar spectrum diagnostic scale in Argentinean patients with mood disorders

Objective

To assess the sensitivity and specificity of two self-report instruments for detection of bipolarity in a sample of Argentinean patients.

Method

Spanish versions of the MDQ and the BSDS were administered over four months at 11 sites in Argentina. Diagnoses were made using DSM-IV criteria and the MINI. The study sample consisted of patients diagnosed with Bipolar Disorder (BD) Types I, II, or NOS. BDNOS diagnoses were made using extended guidelines for bipolar spectrum symptoms. Unipolar patients were used as a control group. Of 493 patients screened, 354 completed evaluation by MDQ and MINI, and 363 by BSDS and MINI.

Results

Specificity of MDQ was 0.97 and BSDS was 0.81. MDQ sensitivity was 0.70 for bipolar type I (BD-I), 0.52 for bipolar II (BD-II) and 0.31 for bipolar not otherwise specified (BDNOS). BSDS sensitivities were 0.75, 0.70 and 0.51 respectively.

Limitations

This study was performed in specialized outpatient settings and thus its results are not necessarily representative for other clinical settings. There was not a systematic evaluation of comorbid psychiatric disease or test-retest reliability.

Conclusion

The local versions of the MDQ and the BSDS showed a sensitivity and specificity comparable to previous research. Our results indicate that in this sample, MDQ was more specific for BD and BSDS was more sensitive to detect BD-II and NOS. Since BD-I is more readily recognized than bipolar spectrum disorders, enhanced sensitivity of BSDS for soft bipolarity may be an advantage.     

The high prevalence of obstructive sleep apnea among patients with bipolar disorders

Introduction: Sleep plays an important role in maintaining stability in bipolar disorders, and sleep disturbances can trigger mood episodes. Obstructive sleep apnea (OSA) is a common sleep disorder, yet the co-occurrence with bipolar disorder has not been methodically studied. Methods: This is a chart review of 482 consecutively seen patients with a bipolar disorder who underwent routine screening for OSA using a self-report sleep apnea questionnaire. Positive screens were referred for a sleep study. Results: A positive screen was found in 214 (44.4%) patients. Sleep studies were obtained on 114 patients, and 101, were diagnosed with OSA: point prevalence 21%. Discussion: The 21% prevalence fails to consider the false negative rate of the questionnaire, or the exclusion of patients who screened positive but failed to get a sleep study. Taking these into consideration it is estimated that the true prevalence of OSA in this study may be as high as 47.5%. The co-occurrence of OSA and bipolar disorders is markedly higher than previously thought. Of note, OSA may play a role in refractory bipolar, disorders, and carries significant mortality and morbidity that overlap, with the mortality and morbidity found with bipolar disorders. Limitations: This was a retrospective study based on a self-report questionnaire. Polysomnographic confirmation was performed in only a subgroup of subjects. Conclusions: The data suggest that unrecognized OSA may play a major role in the mortality and morbidity of bipolar disorders. All patients diagnosed with a bipolar disorder should be screened with an OSA questionnaire.     

Psychosocial disability and work role function compared across the long-term course of bipolar I, bipolar II and unipolar major depressive disorders

OBJECTIVE: The research literature on psychosocial disability and work in mood disorders has either focused on relatively short-term course, or did not consider direct comparisons of these domains across all three of the affective subtypes of bipolar I (BP-I), bipolar II (BP-II), and unipolar major depressive disorders (UP-MDD). METHODS: Mean composite measures of psychosocial impairment and months at specific levels of overall and work impairment were compared for 158 BP-I, 133 BP-II, and 358 UP-MDD patients based on semi-structured interviews conducted during 15 years of follow-up in the NIMH Collaborative Depression Study (CDS). These are contrasted with a single month of psychosocial impairment ratings for a sample of 1787 subjects with no current psychiatric disorder. RESULTS: Patients with mood disorders experienced some degree of disability during the majority of long-term follow-up (54 to 59% of months), including 19 to 23% of months with moderate and 7 to 9% of months with severe overall impairment. Severe disability occurred a substantial percentage of time only in the specific area of work role function. BP-I patients were completely unable to carry out work role functions during 30% of assessed months, which was significantly more than for UP-MDD and BP-II patients (21% and 20%, respectively). CONCLUSIONS: These findings have public health, economic, and clinical importance, and underscore the need to reduce the chronicity and impairment associated with these three prevalent affective disorder subtypes. Interventional research is just beginning to address these challenges.     

Memory mood congruency phenomenon in bipolar I disorder and major depression disorder patients

The objective of the present study was to evaluate memory performance in tasks with and without affective content (to confirm the mood congruency phenomenon) in acutely admitted patients with bipolar I disorder (BD) and major depression disorder (MDD) and in healthy participants. Seventy-eight participants (24 BD, 29 MDD, and 25 healthy controls) were evaluated. Three word lists were used as the memory task with affective content (positive, negative and indifferent). Psychiatric symptoms were also evaluated with rating scales (Young Mania Rating Scale for mania and Hamilton Depression Rating Scale for depression). Patients were selected during the first week of hospitalization. BD patients showed higher scores in the word span with positive tone than MDD patients and healthy controls (P = 0.002). No other difference was observed for tests with affective tone. MDD patients presented significantly lower scores in the Mini-Mental State Exam, logical memory test, visual recognition span, and digit span, while BD patients presented lower scores in the visual recognition test and digit span. Mood congruency effect was found for word span with positive tone among BD patients but no similar effect was observed among MDD patients for negative items. MDD patients presented more memory impairment than BD patients, but BD patients also showed memory impairment.     

Regional brain gray matter abnormalities in patients with bipolar II disorder: A comparison study with bipolar I patients and healthy controls

Despite the high prevalence and clinical significance of bipolar II disorder (BD II), the underlying pathophysiology is not well explored in previous studies. The purpose of the current study was to investigate brain gray matter abnormalities in BD II. High resolution magnetic resonance brain images from 23 BD II patients, 23 sex- and age-matched patients with bipolar I disorder (BD I) and 23 healthy controls were acquired and processed according to the optimized voxel-based morphometry protocol. The processed gray matter tissue volumes were compared among the three groups. Both the BD II and BD I group showed gray matter deficits in the ventromedial prefrontal regions, compared to controls. The BD I group had widespread gray matter reductions in the bilateral frontal, temporal, parietal and parahippocampal cortices, compared to controls. However, gray matter reductions in these regions were not found in the BD II group. With a less conservative statistical threshold, the BD II group showed additional gray matter deficits in the anterior limbic cortices. Our data suggest that gray matter deficits in the ventromedial prefrontal and anterior limbic cortices are common in both BD II and BD I. On the other hand, different pattern of gray matter abnormalities between BD II and BD I found in this study supports that two subtypes may have different neurobiological characteristics.     

Prodromes, coping strategies and psychological interventions in bipolar disorders

Bipolar disorder is known to be highly recurrent and people with bipolar illnesses often experience high degrees of interpersonal and social impairment. The emergence of prodromal symptoms not only causes distress but may also predispose patients to greater risk of a full relapse. Studies have found that patients can report prodromes reliably. Common mania prodromes include decreased need for sleep, increased activities, being more sociable and racing thoughts while common depression prodromes are loss of interest, not being able to put worries aside and interrupted sleep. Furthermore, patients' coping with prodromal symptoms predicted relapses in bipolar disorder. These findings have led to a handful of randomized controlled studies which aimed at teaching patients relevant and adaptive coping strategies in dealing with bipolar prodromes as part of the intervention strategies and the results are very encouraging. The packages in these studies are of different complexity. The mode of intervention also varied from individual work, group work to family work. This paper also examines the differential effects of these interventions.     

Risk of developing diabetes mellitus and hyperlipidemia among patients with bipolar disorder,major depressive disorder,and schizophrenia: A 10-year nationwide population-based prospective cohort study

Background

The high comorbidity of metabolic side effects with severe mental disorders (SMDs), including bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia, had gained much attention, because the excess mortality of these patients is mainly due to physical illness. However, most of these studies were with cross-sectional study design, the time course of metabolic side effects and SMD cannot be elucidated without a cohort study.

Method

Using a nationwide database with a large sample size and a matched control cohort study design, we enrolled patients with SMDs but without diagnoses of and medications for DM and hyperlipidemia from 1996 to 2000, and followed them to the end of 2010. We compared them with age and gender-matched controls (1:4) for the incidence of DM and hyperlipidemia.

Results

The identified cases were 367 patients with BD, 417 patients with MDD, and 1993 patients with schizophrenia, with average age of 45.3±14.0, 46.5±13.7, and 45.9±12.3, respectively. The patients with BD and schizophrenia had increased risk of initiation of anti-diabetic medications (10.1% vs. 6.3%, p=0.012; 13.3% vs. 7.2% p<0.001; respectively), and anti-hyperlipidemia medications (15.8% vs.10.5%, p=0.004; 14.2% vs.12.1%, p=0.005; respectively) than the controls. After controlling age, gender, urbanization, and income, the Cox regression model showed significantly increased risk of initiation of anti-diabetic medications among patients with BD (hazard ratio (HR) of 1.702, 95% confidence interval (CI): 1.155–2.507) and schizophrenia (HR of1.793, 95% CI: 1.532–2.098). Increased risk of initiation of anti-hyperlipidemia medications was also noted among patients with BD (HR of 1.506, 95% CI: 1.107–2.047) and schizophrenia (HR of 1.154, 95% CI: 1.002–1.329). The patients with MDD did not show increased risk of initiation of these medications than the controls.

Conclusions

This first 10-year nationwide population-based prospective matched control cohort study showed increased risks of initiation of anti-diabetic and anti-hyperlipidemia medications among patients with BD and schizophrenia. No significant increased risk was noted among the patients with MDD.     

Neuropsychological study of IQ scores in offspring of parents with bipolar I disorder

Introduction: Studies comparing IQ in Offspring of Bipolar Parents (OBP) with Offspring of Healthy Controls (OHC) have reported conflicting findings. They have included OBP with mental health/neurodevelopmental disorders and/or pharmacological treatment which could affect results. This UK study aimed to assess IQ in OBP with no mental health/neurodevelopmental disorder and assess the relationship of sociodemographic variables with IQ.

Methods: IQ data using the Wechsler Abbreviated Scale of Intelligence (WASI) from 24 OBP and 34 OHC from the North East of England was analysed using mixed-effects modelling.

Results: All participants had IQ in the average range. OBP differed statistically significantly from OHC on Full Scale IQ (p?=?.001), Performance IQ (PIQ) (p?=?.003) and Verbal IQ (VIQ) (p?=?.001) but not on the PIQ-VIQ split. OBP and OHC groups did not differ on socio-economic status (SES) and gender. SES made a statistically significant contribution to the variance of IQ scores (p?=?.001).

Conclusions: Using a robust statistical model of analysis, the OBP with no current/past history of mental health/neurodevelopmental disorders had lower IQ scores compared to OHC. This finding should be borne in mind when assessing and recommending interventions for OBP.     

Heritability and linkage analysis of personality in bipolar disorder

Background

The many attempts that have been made to identify genes for bipolar disorder (BD) have met with limited success, which may reflect an inadequacy of diagnosis as an informative and biologically relevant phenotype for genetic studies. Here we have explored aspects of personality as quantitative phenotypes for bipolar disorder through the use of the Temperament and Character Inventory (TCI), which assesses personality in seven dimensions. Four temperament dimensions are assessed: novelty seeking (NS), harm avoidance (HA), reward dependence (RD), and persistence (PS). Three character dimensions are also included: self-directedness (SD), cooperativeness (CO), and self-transcendence (ST).

Methods

We compared personality scores between diagnostic groups and assessed heritability in a sample of 101 families collected for genetic studies of BD. A genome-wide SNP linkage analysis was then performed in the subset of 51 families for which genetic data was available.

Results

Significant group differences were observed between BD subjects, their first-degree relatives, and independent controls for all but RD and PS, and all but HA and RD were found to be significantly heritable in this sample. Linkage analysis of the heritable dimensions produced several suggestive linkage peaks for NS (chromosomes 7q21 and 10p15), PS (chromosomes 6q16, 12p13, and 19p13), and SD (chromosomes 4q35, 8q24, and 18q12).

Limitations

The relatively small size of our linkage sample likely limited our ability to reach genome-wide significance in this study.

Conclusions

While not genome-wide significant, these results suggest that aspects of personality may prove useful in the identification of genes underlying BD susceptibility.